Bear Population Numbers in Southwest Kodiak Improving After Decline

Kayla Desroches/KMXT

This past winter, bear specialists wrapped up the fourth and final year of a partnership between the University of Montana and the Kodiak National Wildlife Refuge which aimed to track how bears respond to salmon runs in southwest Kodiak.

Will Deacy, who just received his graduate degree from the University of Montana, says part of his dissertation work focused on bear movements in response to sockeye spawning. He says over 50 percent of a bear’s diet consists of salmon, and they aim for the best quality of fish they can get. The fresher, the better.

“We did a study a few years ago where we monitored the fat in different salmon using a pretty fancy tool called the fish fat meter, and we find that as they come out of the ocean, sockeye can have 15 percent fat and then only a month later, once they enter streams, they are down to 1 percent fat, so of course a bear if they can will grab that 15 percent fat salmon.”

Over the last few years of studying streams in southwest Kodiak – namely tributaries to Karluk, Frazer, and Red lakes – Deacy says he and his colleagues found that bears are good at moving from place to place to find salmon.

“This is really important because each individual spawning population might only be spawning for two or three weeks, so it’s a very brief time, and if they only ate salmon at that one spot, their salmon consumption would be very low, but by stringing together multiple sites where each population’s providing salmon for three weeks at a time, they can consume salmon for much longer, like three months.”

Deacy says they think that behavior is critical for bears’ diets.

He says they got the idea for the study in 2010 because they saw a large decline in bears in southwest Kodiak, and they began field work in 2012. Across the period of study, they discovered that elderberries and early run sockeye salmon were important to bear diets.

“And what we saw is that the two years preceding the decline documented in 2010, we had very, very low early sockeye escapement in the Karluk Basin, so less than 50,000, which is about a tenth of what had occurred in the high just five years before, and then we also had two very cold, wet years which tend to produce really low berry productivity.”

Deacy says that lack of nutritional resources seems to have been responsible for the bear decline.

He says there’s been a big difference in weather over the years of the study and for the last two years, the salmon runs and berry growth has looked up, as has the population of bear cubs.

“The last two years in particular were very, very warm and that changed the vegetation community for the bears. Normally, salmon runs and berries are available at two different times, and this last two years they occurred at the same time.”

Deacy says his plan moving forward is to take all of the data they’ve collected and create a virtual bear population to test out different conditions and how they could impact bears.

You can hear more about Deacy’s study on Talk of the Rock Tuesday. That’ll be at 12:30 p.m. following KMXT’s midday report.